The Goldfinch was a 2013 novel by Donna Tartt that won the Pulitzer Prize and divided critics, some of whom called its sprawling, 784-page tale childish. It’s now a movie from Warner Bros. and Amazon, with a budget of $40 million, a cast that includes Nicole Kidman, Jeffrey Wright and Ansel Elgort, and its own two-and-a-half-hour sprawl that has not endeared it to its own critics.

But for director John Crowley (Brooklyn) it all started from a very small place. “The Goldfinch” is a 1654 oil painting by Dutch master Carel Fabritius. About the size of the latest laptop, it depicts a tiny bird chained to its perch.

Director John Crowley speaks during a press conference for The Goldfinch at the Toronto International Film Festival.GEOFF ROBINS/AFP/Getty Images

Crowley visited it three times at the Mauritshuis, the art museum in the Netherlands where it hangs. “I was sucker-punched by the power of it,” he recalls of his first viewing. “It’s enormously powerful for this tiny thing.”

Crowley, in Toronto for the world premiere of The Goldfinch, remembers feeling that the painting was looking back at him. “After about five minutes, you’re convinced that that bird is breathing, and that it’s got a tension in it that looks like it’s about to take off and fly, or about to make a noise.”

He was also struck by the quality of light in the work. “It’s a painting that does seem to glow from the inside out,” he says. “It’s like there’s a tiny little bit of a light on inside it. And so I can see why it has a power that could lead one to be slightly obsessive about it.”

In the film, Elgort plays Theodore, a young man who lost his mother when they were in an art gallery during a bombing. (Oakes Fegley plays the character as a boy.) Theo leaves the rubble of the gallery clutching the painting, and a ring that will lead him to a father figure played by Jeffrey Wright. For years, he hides the painting as his guilt over the theft grows.

Crowley returned to The Goldfinch in the Netherlands with Roger Deakins, the famed cinematographer (an Oscar winner for Blade Runner 2049) who was director of photography on the film. Both men grappled with the notion of showing the canvas on the big screen.

“Your relationship to a painting in a museum when you stand and look at it is there’s nothing between you and it,” says Crowley. “And the power of it – it’s the original artefact – will either work on you or it doesn’t. Whereas you point a camera at it and you can’t assume that the camera will capture what is special about the painting. It’s almost like they talk different languages.”

So he and Deakins decided to take a narrative step backwards: “You have to care about the character caring about it, to be concerned about its fate.” But he also rejects the idea that The Goldfinch could be anything; that it’s the movie’s MacGuffin, that Hitchcockian term for whatever it is the character yearns for.

“It can be a very lazy term to mean everything and nothing,” Crowley notes. “I wouldn’t say it’s a MacGuffin. His relationship to it in the film is an emotional one, and he becomes fused to it. He gets stuck in his grief.”

In other words, it had to be The Goldfinch, a fact that Crowley grew even more convinced of after those visits to its perch in the Netherlands, when he swore it was about to take flight. “You think it’s just you projecting – and of course it’s you projecting – but it’s you meeting something illusory which is convincing your brain that it’s real.

“And that’s one of things that Tartt is writing about, which is the nature of what’s real and what’s unreal.” Painting, novel or film, The Goldfinch is all at once.